Ascorbate prophylaxis for corneal haze after photorefractive keratectomy.

Abstract

To evaluate whether prophylactic systemic ascorbic acid influences the average level of haze and the incidence of late onset corneal haze after photorefractive keratectomy (PRK). Two consecutive groups of eyes treated with PRK for myopia with or without astigmatism were retrospectively compared. The patients had been treated similarly, with the exception that systemic ascorbate had been supplied orally in one of the groups. Haze intensity was quantified on a scale from 0 (clear cornea) to 4 (anterior chamber not visible). The diagnostic criterion for late onset corneal haze was a haze grade 2 or higher, occurring 4 to 12 months after surgery. One week, 1, 3, 6, and 12 months after surgery, the group without ascorbate (314 eyes) showed haze of average levels 0.61, 0.51, 0.50, 0.32, 0.10, respectively, and the group with ascorbate (201 eyes) showed haze of average levels 0.38, 0.18, 0.16, 0.09, 0.06, respectively. Comparison of the respective values showed a statistically significant difference between the two groups (P<.01) at 1 week, 1, 3, and 6 months. Late onset corneal haze was observed in 11 eyes in the group without ascorbate, and none was observed in the group with ascorbate (P<.02). This retrospective nonrandomized clinical study suggests that oral ascorbic acid supplementation may have a prophylactic effect against haze development after PRK. However, routine prophylactic use of ascorbate can be recommended only after a randomized, prospective clinical trial substantiates its efficacy.